Ammeter Bypass from scratch?

[Isaiah Estrada]

I know the title doesn’t make sense, but hear me out. We are redoing the entire wiring system on the 68 New Yorker. I’ve completely omitted the original ammeter and had the cluster itself rebuilt with a voltmeter in place that functions, looks and reads like the original. It was a complete custom job and not cheap, but I wanted to keep that original look!

Knowing that I’ve done this, I’m assuming I wouldn’t have to go the MAD route, would I? Is there anything I could do to completely bypass that connection altogether?

 

[Isaiah Estrada]

All work done by Redline Gauge

Looks factory but sure ain’t !

Clock has now been converted to a quartz mechanism

All new lettering / paint and new pointers.

Can’t wait to see it work when I drive the car.

 

[live4theking]

You're probably going to have to take the red and black wires that originally connected to the ampmeter and put them together. Then you will need new wiring to run that slick looking voltage gauge you have.

 

[Isaiah Estrada]

You're probably going to have to take the red and black wires that originally connected to the ampmeter and put them together. Then you will need new wiring to run that slick looking voltage gauge you have.

That’s what I’m thinking! I was wondering if it was “safe” to do or not. Sounds like we will just connect the original 2 ammeter wires and hook up the voltmeter like any other drawing 12v from the fuse box

 

[mrfury68]

That instrument cluster looks amazing. Your new wiring will be more reliable than the OE one. Good luck.

 

[Ross Wooldridge]

@live4theking has it correct. Just make the joint safe and durable. A LOT of amperage can flow through there.

Anything that has a heavy load (headlights, heat/AC and such) would be good if there were independent relays to service those circuits, to take the load.

 

[D Cluley]

The factory wiring runs basically all the power from the alternator to the battery through the bulkhead connector, the ammeter and then back through the bulkhead. The power for everything except the starter and the horn tees off of this wire between the bulkhead and the ammeter.

This sets up 2 weak spots. The connector at the bulkhead & the ammeter (more likely the actual wire connections on the back of the gauge).

The full MAD conversion does 3 things to improve this situation.

1. Connect the Red & Black wires to each other directly bypassing the ammeter. You have already set this up by switching to a voltmeter. I'm not sure what the voltmeter connects to, but I assume that Redline Gauge has that figured out.

2. Eliminate the male & female connectors at the bulkhead and run the Red & Black wires straight through new holes. I'm not totally sold on this one, as it could make future work more difficult by making the underdash & underhood wiring permanently connected.

3. Adding a new wire connecting the alternator & battery that stays under the hood and doesn't pass through the bulkhead at all. The power for the ignition, lights, radio, etc still uses the original wiring, but the current that is charging the battery doesn't have to go through the bulkhead. If you are redoing the wiring anyway I would definitely consider this. The only real downside is it would affect the accuracy of the ammeter that you have already eliminated.

 

[SuperDave]

When I built my 73 'Port, I ran a starter cable (0 gauge?) directly from the battery to the 100 amp alternator, completely bypassing the ammeter. Gauge is defunct now, serves no purpose but as a connecting source to other underdash wiring sources. I use an aftermarket volt gauge to monitor charging condition. With the 12v fuel pump and twin electric cooling fans I added, I didn't want/need all that voltage to melt the bulkhead connector, wires or feeding all that juice thru a 50 yo gauge.

I have plans to rip out the entire gauge assembly and replace it all with modern step motor round sport gauges, I figure then I'll splice the ammeter connections and heat shrink it.

 

[3175375]

View attachment 640220

The factory wiring runs basically all the power from the alternator to the battery through the bulkhead connector, the ammeter and then back through the bulkhead. The power for everything except the starter and the horn tees off of this wire between the bulkhead and the ammeter.

This sets up 2 weak spots. The connector at the bulkhead & the ammeter (more likely the actual wire connections on the back of the gauge).

The full MAD conversion does 3 things to improve this situation.

1. Connect the Red & Black wires to each other directly bypassing the ammeter. You have already set this up by switching to a voltmeter. I'm not sure what the voltmeter connects to, but I assume that Redline Gauge has that figured out.

2. Eliminate the male & female connectors at the bulkhead and run the Red & Black wires straight through new holes. I'm not totally sold on this one, as it could make future work more difficult by making the underdash & underhood wiring permanently connected.

3. Adding a new wire connecting the alternator & battery that stays under the hood and doesn't pass through the bulkhead at all. The power for the ignition, lights, radio, etc still uses the original wiring, but the current that is charging the battery doesn't have to go through the bulkhead. If you are redoing the wiring anyway I would definitely consider this. The only real downside is it would affect the accuracy of the ammeter that you have already eliminated.

I would recommend #3, with a caveat that the wiring inside the cab should be connected to the battery, through the bulkhead connector.

I would have to review the system schematics to exactly figure out how to do that.

Here’s my caveman sketch of what I am thinking: (the green is how I would run wires)